1. Technical Field of the Invention
This invention relates to channel assignments in cellular telephone networks and more particularly, to a system and method for providing priority access and channel assignment (PACA) to designated subscribers.
2. Description of Related Art
The coverage area of a typical cellular telephone network is broken into individual cells. In highly populated metropolitan areas or in times of crisis, congestion occurs in these cells. Even in times of congestion, however, there is a need for some callers, such as providers of emergency services, to have priority for access and channel assignment. An existing prioritization implementation assigns permanently to designated priority users, hereinafter referred to as "PACA users", a bank of reserved channels for the sole use of PACA users. These channels are always reserved, regardless of whether or not the channels are currently needed by PACA users. These reserved channels are utilized either for calls to, or calls from, PACA users. The reserved channels are also available for handoff when a PACA user moves from one cell to another.
The Telecommunications Industry Association (TIA) is currently developing an end user interface standard known as IS-53A. The proposed IS-53A standard does not require a bank of reserved channels, but rather assigns available channels to users based on a predetermined prioritization scheme. The standard specifies that requests for voice or traffic channels by PACA users are queued, and the system handles the queue on a priority and first-come, first-served basis. Thus, as a channel becomes available, it is assigned to the first requesting user having the highest priority level. The proposed IS-53A standard is hereby incorporated by reference herein.
There are several shortcomings with the approach as put forth in the proposed IS-53A standard. First, the queuing approach is not supported by the current air interface. Under the standard, if a mobile subscriber tries to make a call when the networks are congested, he is placed in a queue to wait for an available voice channel. However, without an available voice channel, there is no way for the telecommunication system to tell the subscriber that he is in a queue and that his call will be processed when a channel is available. The subscriber has no way of knowing whether he is waiting for a voice channel, or whether he has lost his transmission connection. Additionally, the standard is only applicable for initiating calls, and does not solve the problem of call termination or prioritization in handoff situations.
U.S. Pat. No. 5,226,071 to Bolliger et al. (Bolliger) discloses a wireless telecommunications system in which call path resources are allocated in an orderly manner by queuing call requests during, for example, channel unavailability, and assigning channels to queued call requests as channels become available. Bolliger is, in essence, a patent on the proposed IS-53A queuing approach. A plurality of queues are provided for different locations within the service area so that, as a mobile station moves, its call request is sequentially placed in different queues. Bolliger states that it is usable for queuing both incoming and outgoing calls, however, there is no disclosure of how such a system for incoming calls would be implemented, and it is not clear that there is any advantage for a mobile station to be placed in a queue for incoming calls.
Since Bolliger is limited to a system based solely on queues, it suffers from the same disadvantages as the proposed IS-53A standard described above. For example, Bolliger does not provide any method of informing a subscriber that he is in a queue. Also, although Bolliger discusses removing a call request from one queue and placing the request in a second queue whenever a mobile station waiting for a voice channel moves from one cell to another, Bolliger cannot be utilized for handoff of an active call since the call would have to be interrupted and placed in a queue whenever a mobile station moved from one cell to another.
Review of each of the foregoing references reveals no disclosure or suggestion of a system or method such as that described and claimed herein.
It would be a distinct advantage to have a system that is capable of utilizing a bank of reserved channels or a combination of reserved channels and queues to provide priority access to PACA users, whether the PACA user is involved in a call origination, call termination, or handoff situation. Such a system would enable a service provider to designate whether to utilize a bank of reserved channels, a queue technique, or a combination of the two for providing priority access to PACA users. The present invention provides such a system.